EFFICIENT LASER OPERATION WITH NEARLY DIFFRACTION-LIMITED OUTPUT FROMA DIODE-PUMPED HEAVILY ND-DOPED MULTIMODE FIBER

Laser performance of a diode-pumped Nd-doped multimode phosphate-glass fiber is reported. The selection of the fundamental mode in a multimo de fiber is demonstrated, resulting in laser emission that is close to diffraction limited and that is nearly independent of the pump power. The heavily Nd-doped fibers with core diameters of 100 mu m and lengt hs between 13 and 32 mm deliver as much as 130 mW of cw output power a t 1.053 mu m. A total efficiency of 31% with respect to launched pump power has been achieved. (C) 1996 Optical Society of America